Abstract: In an effort to understand what happened at the mineral surface or interface during the arsenopyrite（Apy）weathering/oxidation process, and to assess the potential environmental risks of this processand its products as well, fifteen arsenopyrite specimens were cut into cubes (length side about 2.5mm) and reacted with sulphuric acid under 100-300℃ in the reaction pots. The pH levels of the acid solutions are 0, 1, and 3, respectively. Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) was taken to analyze the remaining solutions after reaction. The productspresentat the residual solid surface were tested by the X-ray Photoelectron Spectroscopy (XPS)，Electron Probe Microanalysis (EPMA) and X-ray Powder Diffractometry (XRD). Scanning Electron Microscopy (SEM) was used to accomplish the morphological analysis. Results from ICP-AES present that a large number of As move into solution (the valence untested), and the level of total As ion in the solution significantly increased with the rise of temperature and acid concentration. Themorphological observation from SEM shows that the dissolution of arsenopyrite starts from the edges of cube and the fracture. Then, thereaction interface gradually migrates into the innerpart of the arsenopyrite cube. XPS narrow scan of the residual solid surface indicates that Fe3+, S8, SO32-, SO42-, As3+, As5+ and a small amount of As1+ are generated at the surface, among whichAs3+ dominates. XPS profile analysis of As 2p3/2 manifests that with the increase of the erosion depth, the concentration of oxidized As grows -- the reaction prompts arsenopyrite to oxidize and generates the oxidation state of As. Due to a mass of oxidized As being transferred to the solution from the As-containing minerals and rocks, the oxidation of arsenopyrite means As would be released into the superficial water and participate in the groundwater circulation, and thus, pose a huge potential threat to the ecological environment.